In Harlem, con artist Deke "Reverend" O'Malley [Calvin Lockhart] pitches a scheme at a rally to fund a Back-to-Africa voyage aboard a ship named The Black Beauty. As the crowd cheers, masked gunmen leap from a meat truck and swipe $87,000 donated cash from the back of an armored car. In the ensuing chase, a bale of cotton tumbles from the getaway vehicle, a clue that goes unnoted by the authorities at first.
His pursuers arrive: Gravedigger Jones [Godfrey Cambridge] and Coffin Ed Johnson [Raymond St. Jacques], two Harlem detectives who see through the ruse and suspect the con. Captain Bryce [John Anderson], who keeps a Nixon portrait on his wall, orders the officers to drop the case and not treat O'Malley as a suspect. The investigators go to Iris Brown's apartment, where Iris is guarded after O'Malley’s supposed visits, but Iris manages to slip away when help is momentarily distracted. She later discovers O'Malley entangling with Mabel Hill [Emily Yancy], leading to a tense confrontation between the two women and a dawning disillusionment about the Reverend.
Uncle Budd [Redd Foxx], a scavenger with a nose for easy money, finds the cotton bale and pockets it for $25, only to buy it back for $30. A reward for the stolen cash stirs up trouble, and Gravedigger and Coffin quickly deduce that the money is hidden inside the bale, triggering a violent scramble as rival gangs close in on the prize. Iris shares a crucial truth with the detectives: the robbery was part of O'Malley's plan to seize the funds without rocking his image, but his partner Calhoun [J.D. Cannon], a white career criminal he met in prison, double-crossed him and intends to take the money for himself.
Calhoun abducts Iris to force the location of the bale from her, leading to a deadly shoot-out in which Jones and Johnson come to Iris's rescue. Later, at a Harlem theater, Iris's friend Billie—the dancer played by Mabel Robinson [Mabel Robinson]—uses the bale as a prop in her act, drawing both Calhoun and O'Malley to the stage. In the back of the theater, Johnson clashes with O'Malley, and Jones and Johnson arrest Calhoun, who is masked in blackface, exposing O'Malley's fraud to the audience. The crowd turns on him as he pleads for support, and the pair leave him to face the consequences.
With the audience gone, Jones and Johnson hustle Tom, a white mob leader, to hand over the $87,000 to the original donors. Meanwhile, Uncle Budd has vanished with the loot and emigrates to Ghana, living in retirement with his ill-gotten gains and a harem, a final act that underscores the detectives’ relentless pursuit of accountability in a city of shifting loyalties.
